DPP-4 inhibitor induces FGF21 expression via sirtuin 1 signaling and improves myocardial energy metabolism

Figures

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  Fig. 1. Effect of vilda treatment on cardiac hypertrophy and dysfunction in pressure-overloaded non-diabetic mouse heart. a Heart weight/tibia length ratio (HW/TL). b Fractional shortening (FS) measured by echocardiography. Open bar, vehicle-treated; closed bar, vilda-treated (a, b; Cont with vehicle, N = 6; Cont with vilda, N = 6; TAC with vehicle, N = 9; TAC with Vilda, N = 10). c–f Conductance catheter measurements (N = 5–7 of each group). Open bar, vehicle-treated; closed bar, vilda-treated. LVESP, left-ventricular end-systolic pressure (c); LVEDP, left-ventricular end-diastolic pressure (d); SW, stroke work (e); efficiency estimated by SW/pressure–volume area (f). g Myocardial fibrosis area estimated by Masson’s trichrome staining. h, i Glucose uptake and free fatty acid (FFA) uptake in hypertrophied heart and vilda’s effect. Glucose uptake was estimated by 18F-FDG (2-fluorodeoxyglucose) uptake in heart (h). FFA uptake was estimated by 125I-BMIPP uptake in heart (i). Statistical analysis was performed unpaired two-tailed Student’s t test with Welch’s correction. *P < 0.05 vs control. †P < 0.05 vs vehicle-treated group

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  Fig. 2. Representative PV loop after TAC

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  Fig. 3. Vilda increased cardiac FGF21 expression levels in non-diabetic mouse heart with TAC. Open bar, vehicle-treated; closed bar, vilda-treated. a Myocardial FGF21 mRNA expression by real-time RT-PCR. b Representative western blot of mouse heart. c–f Summarized protein expression data for FGF21 (c), Sirt1 (d), phosphorylation levels of AMPK (e), and FoxO3a (f) estimated by the ratio of phosphorylated protein and total protein intensities. N = 4 for each experiment. Statistical analysis was performed unpaired two-tailed Student’s t test with Welch’s correction. *P < 0.05 vs control. †P < 0.05 vs vehicle-treated group

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  Fig. 4. Fluorescent immunostaining of heart sections from 3-week TAC mice. Representative fluorescent immunostaining images. Vehicle-treated sham-operated (a), vilda-treated sham-operated (b). Vehicle-treated TAC-operated (c) and vilda-treated TAC-operated (d). FGF21 (green), Tropomyosin (myocytes) (red), and WGA staining (membrane/extracellular matrix) (blue). Dotted circles indicate non-myocyte positive staining for FGF21. Scale bars: 50 µm

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  Fig. 5. Vilda induces FGF21 expression through the Sirt1 pathway in human cardiac fibroblasts (HCF). a Western blot analysis of the effect of vilda treatment on FGF21 protein levels in HCF. Summarized data for FGF21 are shown in b (N = 4 for each experiment). Statistical analysis was performed unpaired two-tailed Student’s t test with Welch’s correction. *P < 0.05 vs 0 nM. c Gene silencing effect of DPP4 induced by siDPP4 transfection on FGF21 expression in HCF. Summarized data for FGF21 are shown in d (N = 3 for each experiment). Statistical analysis was performed unpaired two-tailed Student’s t test with Welch’s correction. *P < 0.05 vs siGFP. e–g Time course after vilda stimulation (10 nM) in HCF. A representative western blot analysis of FGF21, Sirt1, and P-AMPK protein expression in HCF treated with vilda for 8 or 24 h (e). f, g are summarized data for FGF21 (f) and Sirt1 (g) (N = 4 for each experiment). Sirt1 activator (Resveratrol: 50 nM) induced FGF21 protein expression in cell lysates of HCFs (h). Statistical analysis was performed unpaired two-tailed Student’s t test with Welch’s correction. *P < 0.05 vs vehicle. ELISA for FGF21 in medium supernatant of HCF stimulated with…

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  Fig. 6. A schematic illustrating the Sirt1–FGF21 axis and vilda-mediated cardiac protection. Vilda-induced FGF21 expression in cardiac fibroblasts via Sirt1 and increased myocardial energy metabolism through fibroblast–myocyte interaction. Pressure overload induces cardiac-fibroblast activation in the heart, resulting in the fibroblast-mediated FGF21 pathway dominating (lower). Unknown inhibitory pathway(s) for FGF21 activation in activated cardiac fibroblasts is proposed to account for this observation